10GBE ISCSI direct attached

When I first heard a customer suggest they had been told by a competitor that 10GBE ISCSI directly connecting their two hosts to their SAN was ok, I immediately scoffed and said "not a good idea". When asked "why?" I spluttered a bit and said, "because its not good practice".....scratching my brain further I said, "its encapsulated so it has overhead in comparison [to the direct connect SAS solution we recommended]" ....a pretty weak excuse given that would be true regardless if switches were used.

Aside from that I struggled to think of a good reason. I knew it would work as I have direct connected ISCSI for troubleshooting purposes many times. However for a non scaling DR site (never going to grow beyond the two hosts for this solution) why isn't 10GBE direct connected a good idea?...

I had a client before that only had 1 cluster of 2 hosts connected to a SAN and it was connected directly via FC quite happily, and using multipath as each host had 2 connections, one to CTL-A and the other to CTL-B, using all 4 FC ports of the SAN.

The trouble came when they wanted to add a second cluster, when we had to connect one host to each port, losing multipathing.

At the end they had to buy a couple of brocades, do zoning, and setup a proper SAN Fabric, but until then direct fibre worked fine for they small environment.

So, I can't see why not direct 10GbE won't be recommended for small clients, the only drawback, is that as soon as the company grows they will have to build a fabric. But this move might save a small company a few bucks for a couple of years, and if the hosts connected are powerful VMware hosts, it will buy even more time.

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